Nonstatic photographic film



Jan. 19 1926. 1,570,076

E. C. PITMAN NoNsTATIc PHoToGRAPHlc FILM Filed Sept. 16, 1920 'lm fbrmer (fo/comb) 5. C. PIT/nan, Inl/enfer' y [1115' offer/MyW Patented Jan. 19, 1926.

UNITED STATES EABLE C. PITMAN, OF PARLIN, NEW J' ERSEY ASSIGNOR TO E. I. DU PONT DE NEMOURS PATENT OFFICE.-

& COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE.

NONSTATIC PHOTOGBAPHIC FILM.

Application led September 16, 1920. Serial No. 410,746.

To all whom it may concern:

Be it known that I, EARLE C. PITMAN, a citizen of the United States, and a resident of Parlin, in the county of Middlesex and State of New Jersey, have invented a certain new and useful Nonstatie Photographic Film, of which the following is a specification.

This invention relates to photographic films having provisions for the elimination of discharges of static electricity. With the ordinary film these discharges occur when the film is stripped from the casting surface, when it is run rapidly through a cinematographic camera and under various other circumstances. Such discharges cause markings on the sensitized emulsion by premature exposure thereof. It is an object of the invention to provide a film which, for practical purposes of manufacture and use, will be free from static electricity, and it is also an object to improve generally upon films of the charac-ter indicated.

For convenience and brevity of description I use the term film to denote the entire article, whether or not the article includes a sensitized emulsion; the term film body to denote the entire emulsion support whether or not that support is composed of a plurality of layers, sub-films or pellicles; the term backing to denote a layer of a composite film body, which lies adjacent the other side of the film body from the side intended to directly carry the emulsion; and I use the term base to denote the portion of a composite film body which is intended to carry the backing at one side and the emulsion at the other and to forni or include the principle strength-giving portion of the film. On occasion, as will appear from the context, I use the term base (or pellicle base) to also indicate the substance, as cellulose nitrate, Which is the primary substance used to form a pellicle.

.In the accompanying drawing I have, without restricting my invention thereto,

shown a film embodying my invention, the

awa be neutralized, crabe evenly distrib.

nte before they can accumulate in such a Way, or to such amount, as to be liable to harmful discharge.

Thus, I may incorporate in the body a hygroscopic substance such as glycerine; an electrolyte such as sodium or ammonium acetate, or magnesium nitrate; or a film former such as saponin, alkali saltsof unsaturated fatty acids (such as sodium sulphoricinoleate), alkali salts of egg albumin, or alkali salts of aromatic sulphonic acids; or I may use any of the various combinations of substances of these general characters that I may desire, the substances selected for any specified case to be soluble in the particular solvent mixture used for making the pellicle in which the substances are to be incorporated, and to be such as not to cause precipitation of the pellicle base. as nitrocellulose, used for the pellicle. The hygrosco ic substance increases the conductivity by increasing the moisture content, and the electrolyte increases the conductivity of any moisture present. A film former, acts to convert the isolated drops of moisture, co1- lecting on the film, into a homogeneous continuous film, thereby increasin conductivity. Both the electrolyte and the fi m former are, of course, valuable whether or not a hygroscopic substance is used also, as some moisture is present in'any case. c

In general, and as previous] mdlcated, a film body, i. e. the entire emu sion support, may consist of one layer only; or may consist of a plurality of layers, one of the layers being the backin and the remainder of the body being the ase or principal strength its non-conductivity. So, in carryin giving layer or layers of the film body. When incorporating the various substances, e. g. sodium acetate and so on, in accordance with the invention, they may be placed 1n a film body not comprising a backing and made from any desired pellicle base, e. g. cellulose nitrate; or such substances may be, in the first instanceP placed in a backing and such backin a plied to any desired base layer. The acllging may be one which primarily functions merely y virtue of the substances and, so, may not contain a pellicle base, e. g. nitrocellulose; or it may contain a pellicle base of any suitable character and either having substantially the same conductivity as the ellicle base used in making the base of the hlm, or having a conductlvity somewhat greater than that of the pellicle base used in makin enabling the pellic e base of the backing to itself serve in giving the backing a superior conductivity.

As to the use for the `backing of a pellicle base which is itself of superior conductivity, I may apply a backing layer of carbohydrate ester of relatively low, esterification, e. g. cellulose nitrate of 111% or less nitrogen content, that is, of not over 11i/2% nitrogen content. lose nitrate decreases in hygroscopicity and in conductivit creases, though it increases in strength, so that cellulose nitrate of not over lll/2% nitrogen content is more hygroscopic and more conductive than cellulose nitrate of mom than 11i/2% nitrogen content; yet exrience has shown that, if proper stren h 1s to be secured in a cellulose nitrate m, then a film primarily of cellulose nitrate of more than lll/2% nitrogen content is a practical necessity, despite the fact that, used alone, it is liable to static discharges due to out my invention, I apply a backing of cel ulbse nitrate of 11i/2% or less nitrogen content, preferably about 10.9%, to a base of celluff ose nitrate having more than 11%% nitrogen content, preferably about 11.8% to 12%. In this way I produce a nitrocellu-j lose film which has the strength demanded by the trade and yet is conductive and substantially non-static. As will be understood, a film of the character just indicated may, if desired, contain no added hygroscopic, electrolytic or film-forming substances and yet present the advantage of conductivity to a marked degree. In such cases, anyV suitable formulas for the base and the backin solutions may be used; conveniently, the be owygiven formulas 4,,and l or 4, each with the sodium acetate omitted, may be used for the base, and the backing, respectively.

While the above mentioned nitrocellulose backing is highly advantageous of itself the base of the film and I have found that cellu- I as the nitrogen content insodi either when ap lied to any suitable film base or, artcu arly, when applied to the mentione nitrocellulose film base, I have found, as previously indicated, that the incorporation in such a backing of conductivity-increasing substances, such as a hygroscoplc substance, an electrolytic substance, or a film-forming substance, or any combinations of these, gives a particularly satisfactory film.

The mechanical operations of makin films in accordance with my invention wil be evident to those skilled in the art, the castin of films, and similar operations, as such, eing of course well known in the art. The backing solution may be applied, and the solvents evaporated to give the backing, in any convenient manner. Below I give formulas illustrative of films embodying m invention, it being understood that I do not restrict the invention to the examples given. In the formulas, figures refer to parts by Weight.

(1) For a backing containing an electrolyte, sodium acetate, the followingformula may be used Approximate Prennge. ferred.

Cellulose nitrate (dry) 4 to 16 l um acetate (Nane 3H10) 0. 25 to 16 1 Wood alcohol 100 to 150 120 Aeetone 10 to 60 20 Fusel oil 10 to 50 40 Amyl metete.T 10 to 40 20 In making up, to the combined solvents add (a) the sodium acetate and (b) the cellulose nitrate, in order.

(2) For a backing containin an electrolyte, sodium acetate, and a film ormer, saponin, the formula, as to ingredients, ranges and preferred amounts,l may be the same as for llexcept that it should in addition include approximately 0.005 to 0.20 part, preferabl 0.02 part of saponin. In making up, add a) the sodium acetate, (b) the saponin, and c) the cellulose nitrate, in order to the combined solvents.

(3) For a backing containing a hydroscopic substance, glycerine; an electrolyte, sodium acetate, and a film-former, saponin, the formula, as to ingredients, ranges, and preferred amounts may be the same as for 2, except that it should include in addition approximately 0.25 to 16 parts, preferably 1 part, of glycerine. to the combined solvents add (a) the so.- dum acetate? (b) theg glycerine, (c) the saponin, and (d) the cellulose nitrate, in order.

While the various backings ma be of any desired thickness serving the en s soughtz I have found a relatively thin backin des1r able. A film base for them ma e 4, sodium acetate omitted.

In preparlng,

(4) For a film body, not having a backing but yet containing an electrolyte, sodium aceate, I recommend the following formu a Approximate Pre- Range. ferred.

Cellulose nitrate (dry) 25 to 50 35 Sodium acetate 0.25 to 10 1 Cam hor 2 to 6 4 W alcohol.- 90 to 150 120 Acetone 10 to 60 20 Fuseloll 20 to 50 40 Amylaoetate 10 to 30 20 When making up, add (a) the sodlum acetate, and b) the cellulose nitrate in order, to the com ined solvents. ,y

(5) For a similar film body and containing an electrolyte, sodium acetate, and a film former, sapomn, the formula, as to ingredients, ranges, and preferred amounts, may be the same as 4 except that it should include, in addition, approximately 0.0125 to 0.3 part, preferably 0.05 part, of sa onin. )Vhen reparing, to the combined so vents add (a the sodium acetate, (b) the saponin, and (c the cellulose nitrate, in order.

(6) or a similar film bod containing a 'hygrosco ic substance, glycerme, an electrolyte, so um acetate, and a film former, saponin, the formula, as to ingredients, ranges, and preferred amounts, may be the Same as 5 uexcept that it should include, in addition, approximately 0.5 to 10, preferably 2, parts of glycerine. In making up, to the combined solvents add (a) the sodium acetate, (b) the' glycerine, (c) the saponin, and (d) the cellulose nitrate, in

f order.

`In all the above formulas the nitrocellulose may have lll/2% or less nitrogen content or may have more than 11%% nitrogen content but, as explained above, it is d esirable that nitrocellulose having a nitrogen content of 11i/2% or less, that is, not over 11i/2% nitrogen content, be used for the` backings, and that such backingls be applied to a base of cellulose nitrate aving more than 11i/2% nitrogen content. In the cases of unbacked films it is desirable to use cellulose nitrate having more than lll/2% nitroence to cellulose nitrate as the pellicle base to be used for the various layers, it is to be understood that I do not restrict my invention to the use of cellulose nitrate. Il have found that the relations, as regards conductivity, hy roscopicity, and strength, existing between a) cellulose acetate havin more than 55% combined acetic acid and b) cellulose acetate havin 55% or less, that is not over 55%, com ined acetic acid, are closely com arable to the relations existing between (a cellulose nitrate of more than lll/2% nitrogen content (b) cellulose nitrate of l11/% or less nitrogen content, the hygroscopicity and conductivity of cellulose acetate decreasing as the percentage of combined acetic acid increases., I have also found that cellulose acetate of either type is well capable of valuable use, with or without the addition of other substances, i. e. a hygroscopic material, an electrolyte, a film former, in ways substantially similar to those discussed above; and a cellulose acetate of low esteriieation, e. g. not over 55% combined Vacetic acid, and oontainin or not containing the said substances, can e used to back a base of nitrocellulose .of high esterification, e. g. more than lll/2% nitrogen content and, similarly, cellulose nitrate of low esterification, e. g. not over 11i/2% nitrogen content and containing or not containing the said substances, can be used to back a base of cellulose acetate of high esterification, e. g. more than 55% combined acetic acid; the advantage of increased conductivity being obtained in each case. Also starch acetate, more particularly of the hot- Water-soluble type, is more conductive and hygroscopic than the ordinary film and is capable of desirable use, more particularl as a backing, either with or without additional substances of the types mentioned.

While, in describing my invention, I have referred to it as embodied in a body without a backing and as embodied in a backing it is to be understood that by neither of these terms dor I exclude films wherein the pellicle which more articularly exemplies the invention may ave applied to its (normally) exposed surface a coating of such character as not to destroy the ellicac of the pellicle, the pellicle, from ythe stan point of the present invention, vet being without a backing or being a backing as the case ma be.

Of course, s ouldy it be desired for any reason, both the film base and the hacking of a backed film may contain the conductivity-increasing substances.

I claim:

1. A photographic film having a backing containing sodium acetate.

2. A photographic lilm containing an electrolyte and a film former.

3. A photographic film containing sodium acetate and a film former.

4. A photographie film containing an electrolyte and sa onin.

5. A photograp ic film containing sodlum acetate and saponin.

6. A photographie film containing a hygroscopxc substance, an electrolyte and a film former.

7. A photographic film containing glycerine, an electrolyte, and a film former.

8. A photographic film containing a hygroscopic substance, sodium acetate, and a film former.`

9. A photographic film containing a hygroscopic substance, an electrolyte, and saponln.

10. A photographic film containing a hygroscopic substance, sodium acetate, and saponin.

11. A hotographic film containing glycerine, so ium acetate, and a film former.

12. A photographic film containing glycerine, sodium acetate, and saponin. I

13. A photographic film having a cellulose ester base, and a backing containing sodium acetate.

14. A photographic film having a base and a backing, said backing comprising 4 to 16 parts of a pellicle base and 0.25 to 16 parts of sodium acetate. n

15. A photographic film having a base and a backing, said backing comprising 8 parts of a pellicle base and 1 part of sodium acetate.

16. A photographic film having a base and a backing, said backing comprising 44 to 16 parts of a pellicle base, an electrolyte, and 0.005 to 0.20 part of sappnin.

17. A photographic film 'having a base and a backing, said backing comprising 8 parts 'of a pellicle base, an electrolyte, and 0.02 part of saponin.

18. A photographic film having a base and a backing, said backing comprising 4 to 16 parts of a pellicle base, 0.25 to 16 parts of glycerine, an electrolyte, and a film former.

19. A photographic film having a base and a backing. said backing comprising 8 parts of a pellicle base, 1 art of glycerme, an electrolyte, and a film' ormer.

20. A photographic film having a base and a backing, said backing comprising 4 to 16 parts of a pellicle base, 0.25 to l16 parts of glycerine, 0.25 to 16 parts of sodium acetate, and 0.005 to 0.20 part pf saponin.

'21. A photographic film having a base and a backing, said backing comprising 8 parts of a pellicle base, 1 part of glycerme, 1 part of sodium acetate, and 0.02 part of saponin.

22. A photographic film having a base and a backing, theY pellicle-forming constituent of said backing having a greater conductivity than said base.

23. A photographic film having a base and a backing of carbohydrate ester, sai ester having a greater hydroscopicity than said base.

24. A hotographic film having a. base of carbohy rate ester, and a backing also of carbohydrate ester, the ester of said backing having a greater hygroscopicity than the ester of said base.

25. A photographic film having a base of "esterified cellulose, and a backing also of esterified cellulose, the esterification of the cellulose of said backing being relatively less than that of the cellulose of said base.

26. A photographic film having a backing of cellulose nitrate whaving a nitrogen content of not over 111/296.

27. A photogra hic film having a base and a hacking eac of cellulose nitrate, the cellulose nitrate of said backing being of. greater hygroscopicity than the cellulose nitrate of said base.

28. A photographic film having a base and a backing each of cellulose nitrate, the cellulose nitrate of said backing being of lower nitrogen content than the cellulose nitrate of said base.

29. A photographic film having a base and a backing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than 11i/2%, and the cellulose nitrate of said backin having a lower nitrogen content than has t e cellulose nitrate of said base.

30. A photographic film having a base and a backing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than 1l%%, and the cellulose nitrate of said backing having a nitrogen content of not over lll/2%.

31. A photographic film having a base of low conductivity, relative to that of the hereafter namedpellicle-forming constituent of the backing, and a backing the pellicle-forming constituent of which is. more conductive than said film base, said backing containing a conductivity-increasing substance. n i

32. A photographic film having a backing of cellulose nitrate containing a conductivity-increasing substance.

33. A photographic film havin a cellulose ester base, and a backing o cellulose nitrate containing a conductivity increasing substance.

34. A photographic film having a hacking of cellulose nitrate containing an cleo- Ytrolyte.

435.A A photographlc film having a cellulose ester base, and a backing of cellulose nitrate containing an electrolyte.

36. A photographic` film having a layer of cellulose nitratehaving a nitrogen content of not over lll/2% 'and said layer containing a conductivity-increasing substance.

37. A photogra hic film having a base and a backing eac of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than lll/2%, and the cellulose nitrate of said backing havinga nitrogen content of not over lll/2%, said backing containing a conductivity-increasing substance.

38. A photographic film having a base and a backing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than lll/2% and the cellulose nitrate of said backing having'a nitrogen content of not over lll/2%, said backing containing 4 to 16 parts of cellulose nitrate and 0.25 to 16 parts of sodium acetate.

39. A `photographic film having -a base and a backing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than 111% and the cellulose nitrate of said backing having a nitrogen content of not over lll/2%, said backing containing 8 parts of cellulose nitrate and 1 part of sodium acetate.

40. A photographic film having a base and a backing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than lll/2% and the cellulose nitrate of said backing having a nitrogen content of not over lll/2%, said backing containing 4 to 16 parts of cellulose nitrate, an electrolyte, and 0.005 to 0.20 part of saponin.

41. A photogra hic film having a base and a backing eac of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than lll/2% and the cellulose nitrate of said backing having a nitrogen content of not over 11i/2%, said backing containing 8 parts of cellulose nitrate, an electrolyte, and 0.02 part of saponin.

42. A photogra hic film having a base and a backing eac of cellulose nitrate, the cellulose lnitrate of said base having a nitrogen content of more than 11i/2% and the cellulose nitrate of said backing having a nitrogen content of not over lll/2%, said backing containing 4 to 16 arts of cellulose nitrate, 0.25 to 16 parts of g ycerine, an electrolyte, and a film former.

43. A hotographio film having a base and a bac ing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than 11i/2%, and the cellulose nitrate of said backing having a. nitrogen content of not over lll/2%, said backing containing 8 parts of cellulose nitrate, 1 part of glycerine, an electrolyte, and a film former.

44. A photographic film having a base and a backing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than lll/2%, and the cellulose nitrate of said backing having a nitrogen content of not over llt/2%, said backing containing 4 to 16 parts of cellulose nitrate, 0.25 to 16 parts of glycerine, 0.25 to 16 parts of sodium acetate, and 0.005 to 0.20 part of saponin.

45. A photographic film having a base and a backing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than 11V2%, and the cellulose nitrate of said backing having a nitrogen content of not over 111%%, said backing containing 8 arts of cellulose nitrate, 1 part of glycerine, 1 part of sodium acetate, and 0.02 part of sa onin.

In testimony whereof I a x my signature.

EARLE C. PITMAN.

taining a conductivity-increasing substance.

37. A photographic film having a base 1nd a backing each of cellulose nitrate, the cellulose nitrate of said base having a. nitrogen content of more than lll/2%, and the cellulose nitrate of said backing having a nitrogen content of not over 111/%, sald backing containing a conductivity-increasing substance.

38. A photographic film having a base and a backing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than lll/2% and the cellulose nitrate of said backing having a nitrogen content of not over lll/2%, said backing containing 4 to 16 parts of cellulose nitrate and 0.25 to 16 parts of sodium acetate.

39. A photographic ilm having a base and a backing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than 111/% and the cellulose nitrate of said backing having a nitrogen content of not over lll/2%, said backing containing 8 parts of cellulose nitrate and 1 part of sodium acetate.

40. A photographic lilm having a base and a backing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than lll/2% and the cellulose nitrate of said backing having a nitrogen content of not over 111/270, said backing containing 4 to 16 parts of cellulose nitrate, an electrolyte, and 0.005 to 0.20 part of saponin.

41. A photograhic film having a base and a backing eac of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than 11i/2% and the cellulose nitrate of said backing having a nitrogen content of not over 111/2%, said backing containing 8 parts of cellulose nitrate, an electrolyte, and 0.02 part of saponin.

42. A photogra hic film having a base and a backing eac of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than lll/2% and the cellulose nitrate of said backing having a nitrogen content of not over 11i/2%, said backing containing 4 to 16 parts of cellulose nitrate, 0.25 to 16 parts of glycerine, an electrolyte, and a film former.

43. A hotographic film having a base and a bac ing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than lll/2%, and the cellulose nitrate of said backing having a nitrogen content of not over lll/'70, said backing containing 8 parts of cellulose nitrate, 1 part of glycerine, an electrolyte, and a film former.

44. A photographic film having a base and a backing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than lll/2%, and the cellulose nitrate of said backing having a nitrogen content of not over lll/2%, said backing containing 4 to 16 parts of cellulose nitrate, 0.25 to 16 parts of glycerine, 0.25 to 16 parts of sodium acetate, and 0.005 to 0.20 part of saponin.

45. A photographic lilm having a base and a backing each of cellulose nitrate, the cellulose nitrate of said base having a nitrogen content of more than 111%, and the cellulose nitrate of said backing having a nitrogen content of not over 11i/2%, said backing containing 8 arts of cellulose nitrate, 1 part of glycerlne, 1 part of sodium acetate, and 0.02 part of saponin.

In testimony whereof I atlix my signature.

EARLE C. PITMAN.

Certicate of Correction. It is hereby certified that in yLett/ers Patent No. 1,570,076, grantedlanuary .19,

1926, -upon the a provement in specification requiring correction as hydro read h line 75, a Letters conform to Signed and sealed this 23d day of February,

[SEAL] lication of Earle C. Pitman, onstatic Photographic Films,

follows: Page 2, line 114, for the syllable gro; page 3', line 59, after ter the word content insert t Patent should be read; with these corrections therein that the same may the record of the case in the Patent Oice.

of Parlin, New Jersey, for an 1merrors appear in the printed the fi re 2 insert and 3; Same e wordend; and that the said WM. A. KINNAN, Acting Commissioner of Patents.

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1,570,076, granted January 19, 1926, upon the a lication of Earle C. Pitman, of Parlin, New Jersey, for an improvement in onstatio Photographie Films, errors appear in the printed Specification requiring correction as follows: Page 2, line 114, for the syllable hydr0 read lig/gro; page 3', line 59, after the fi re 2 insert ami 3 same pge, line 75, after the word coutent insert t e word and; and that the said Letters Patent should be madlwith these corrections therein that the same may conform to the record of the case in the Patent O.

Signed and sealed this 23d day of February, A. D. 1926.

[SEAL] WM. A. KINNAN,

Acting Commissioner of Patents. 

